1. Field of the Invention
This invention relates to an epoxy resin composition for semiconductor encapsulation which cures into a product having improved flame retardance, solder crack resistance and dielectric properties. It also relates to a semiconductor device encapsulated with the composition.
2. Prior Art
With the advance of semiconductor devices toward higher density, surface mount packages have now become the mainstream in semiconductor technology. For the manufacture of surface mount packages, vapor phase reflow, IR reflow and solder immersion steps are often employed. These steps expose surface mount packages to high temperatures of 215 to 260.degree. C. Packages encapsulated with conventional encapsulants have the problem that reliability is not insured because cracks are generated in the encapsulant portion during mounting. As thin packages such as TSOP and TQFP now become predominant, the demand for reflow crack resistance is increasing.
In order to increase the operating speed of a CPU, the clock frequency is increased. It is then desired to use for packages and circuit boards, low dielectric constant materials featuring a low loss of signal transmission.
In encapsulating resin compositions, flame retardants such as halogen compounds and antimony trioxide are often blended. However, halogen flame retardants generate halide ions (or radicals) at elevated temperatures, incurring breakage of gold wires and lowering of heat resistance. From the environmental hygienic standpoint, flame retardant encapsulating materials free of halogen compounds and antimony trioxide are desired.
Therefore, an object of the invention is to provide an epoxy resin composition for semiconductor encapsulation which cures into a product having reliability at elevated temperatures, safety to the environment, improved flame retardance, reflow crack resistance and improved dielectric properties. Another object of the invention is to provide a semiconductor device encapsulated with the composition.